1. Field of the Invention
The present invention relates to the field of fixation of anatomical structures, and, in particular, to devices, methods and instrumentation for facilitating bone fusion in an upper extremity of a patient.
2. Description of the Related Art
In some instances bone fusion, or arthrodesis, of anatomy including multiple bone structures may be desirable, such as arthrodesis of the upper extremity bones of the wrist or hand. Wrist or carpus arthrodesis is an established surgical technique to join or fuse adjacent bones in the wrist by rigidly positioning them at their articular surfaces. By maintaining this placement, sometimes in the presence of a bone graft, bone cell growth or other anatomical growth may be stimulated which may cause the bones to fuse together. Once the bones are fixed to one another, all motion that existed at the corresponding joint surfaces of the bones ceases, stability is achieved and any pain caused by the irritation of corresponding nerves is significantly reduced or eliminated. For example, in certain patients with post-traumatic arthritis, rheumatoid arthritis, osteoarthritis, carpal instability, complex or localized fractures or other injury, disease or destructive or painful conditions involving the bones of the wrist, fusion of particular bones of the wrist can alleviate resulting pain, discomfort and instability. Unfortunately, effective fusion of the wrist which balances pain relief, joint stability and retention of some effective movement of the wrist is rarely achieved, no less consistently achieved.
Several surgical approaches have been developed to maximize alleviation of wrist pain and/or instability by arthrodesis. For example, total wrist arthrodesis is very effective in relieving pain, but almost all wrist motion is lost. Since the articulation afforded to the hand by the wrist is important for mobility, strength and dexterity, total wrist arthrodesis is often thought of as a last resort. As another example, limited or partial wrist arthrodesis is often desired in an effort to preserve motion of the wrist to the greatest degree possible. Partial wrist arthrodesis is fusion of a selected group of wrist bones. Variations of the procedure, such as triscaphe, radioscaphoid, radiolunate, scapholunate-capitate and four-corner fusion, attempt to alleviate pain by fusing particular articulations determined or suspected of originating pain and/or instability. Partial wrist arthrodesis is particularly advantageous in patients that desire intricate use of their hands because more residual motion of the wrist can be preserved.
Currently, in both total and partial wrist arthrodesis scenarios, it is common for plates, implants, wires, screws, staples and external fixation devices to be used as the fusion medium. These devices are used alone or in combination to attempt to achieve the desired level of fusion.
The placement and orientation of the bones of the wrist at the time of a wrist fusion is critical to obtaining a bony fusion, preserving maximal wrist motion in partial fusion, and preventing, for example, progressive arthritis of the wrist. One of the drawbacks encountered with prior art partial fusion devices, methods and instrumentation is that they fail to provide consistent and reproducible fusion, and therefore partial arthrodesis rarely results in full relief of pain. For example, when plates, implants, screws and the like are used to achieve partial wrist fusion, the exact placement of the particular plate, implant or screws from surgeon to surgeon and patient to patient are rarely consistent. As such, the predictability of the exact clinical outcome of partial wrist fusion with such prior art devices is low. As a result, there remains much room for improvement in the art for effective fusion devices, methods and instrumentation that provide reproducible alignment, orientation and configuration of the fusion medium with respect to target fixation bones in order to achieve predictable and consistent fusion of such target fixation bones.
Accordingly, it is an object of the present invention to overcome one or more of the above-described drawbacks and/or disadvantages of the prior art. For example, in view of the deficiencies of current designs of partial wrist or hand fusion devices and methods, and similar fusion devices and methods for other areas of the body where multiple bone structures exist including, but not limited to, the foot, ankle and spine, and the lack of proper associated devices, instrumentation and methods to achieve consistent post-operative results, it would be desirable to develop devices, instrumentation and methods to allow a surgeon to achieve satisfactory long term, predictable clinical outcomes for these types of fusion surgeries.